Fermentor for submerged cultures



Feb. 20, 1951 H. HUMFELD ETAL FERIENTOR FOR SUBIIERGED CULTURES 2 Sheets-Sheet 1 Filed Sept. 12, 1947 m M M AN k R DNA 0 awmfiwm W MA HEmw i- Y Feb. 20, 1951 H. HUMFELD EI'AL 2,542,031

FERHENTOR FOR SUBMERGED CULTURES Filed Sept. 12, 1947 Z SheetS-Sheet 2 INVENTORS H.HUMFELD E L AESCHLI MANN BYJ R.HOFFMAN ym.?m

ATTORNEYS Patented Feb. 20, 1951 FERMENTOB FOB SUBMERGED CULTURES Harry Humfcld, Berkeley, Ernst Aeschlimann, Oakland, and John R. Hoi'lman, Berkeley, Calif., assignors to the United States of America as represented by the Secretary of Agriculture Application September 12, 1947, Serial No. 773,722

3 Claims. (Cl. 195-137) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a novel fermentor for submerged cultures.

The use of large vats without agitation devices has been known for generations but has the disadvantage that fermentations carried out under such conditions are comparatively slow and tie up vast quantities of materials as well as requiring large-sized, and consequently expensive, equipment. The trend, therefore, in recent years has been to attempt to use agitation and also to introduce air directly into the reaction mixture.

These developments brought with them serious problems, and foremost among them being foamformation. Both the agitation and the introduction of air caused such large volumes of foam as to render the method impracticable without modification. One remedy involved the addition to the reaction mixture of chemicals having foam-breaking characteristics. This method has the disadvantage of introducing undesired'materials into the system and introduces an unknown factor into an already complicated problem.

We have invented a fermentor by the use of which fermentations can be carried out at extremely rapid rates. Air is added to satisfy the oxygen requirements of the organisms and agitation is employed to bring about intimate contact between the reactants. At the same time the foam formed is broken down, the gas released to the atmosphere, and the liquid returned to the vessel. No foam-breaking chemicals are required. '1' 1) An object of this invention is to provide a fermentor having both novel aeration and foam- F gu e 1;

Figure 3 is a plan view of the foam-breaking disc, illustrating a method of making it;

Figure 4 is an edge view of the disc;

Figure 5 is a pictorial view of the aeration device;

Figure 6 is a top view of the aeration device, the top plate being broken away.

In Figure 1 is shown the assembled device. Vessel I is provided with a lid 2, which serves to cover the contents and to support shaft 3. Shaft 3 extends through lid 2 into the vessel I. Atits lower end, shaft 3 is provided with an enlarged boss 29, having a longitudinal bore 30. Shaft 3 is held in place by collars 4 and 5. At its upper end, shaft 3 is provided with suitable means for rotation, such as an electric motor (not ilustrated) The aeration device is situated at the lower end of shaft 3. This device includes a casing comprisingupper and lower stationary circular plates 23 and 24 fixed in place by pins 26. Upper plate 23 is attached to bars i9 and 20, which in turn are attached to struts I1 and I8. Thus the casing is held stationary. Shaft 3 extends through top plate 23 and is attached at its lower end to 29. To the boss 29, and therefore indirectly to the shaft are attached tubes 28 which extend at right angles to the shaft. The outer ends of the tubes curve rearwardly, opposite to the direction of rotation of the tubes. These tubes communicate with bore 30. Attached to 29 and positioned adjacent of two ofthe tubes are vanes 21. Bottom plate 24 is provided with a port 25 through which extends pipe 2|. The position of this pipe is adjustable to vary the proximity of its tip to the inlet of bore 30; -I'he 30 can be adJusted for the desired'amount of,

air. There is one position of the pipe tip that will give maximum flow of air which can easily be determined with a flow meter." Raising or lowering the tip from this maximum position gives decreasing amount of air flow. Pipe 2| extends from the vicinity of the end of shaft 3 through the vessel I, lid 2, and is open to the atmosphere.

' II, ll.

Shaft 3 is caused to rotate counterclockwise at high speed. Rotation of vanes 21 attached to the shaft causes flow of liquid up through port 25, bore 30, tubes 28 and radially out of the casing past pins 26. Liquid also flows through port 25 directly into the interior of the casing and out past pins 26. The passage of the liquid past the tip of pipe 2| causes air to be sucked through pipe 2| into the liquid stream where it passes through bore 30, tubes 28 and out of the casing. The amount of air entering the system can be regulated by raising or lowering the tip of pipe II as previously described.

Port 25 may be made adjustable in diameter. This can be accomplished by use of rotatable laminae 25'. such as is employedin making iris dlaphragms in photographic cameras. This ad- Justable feature is advantageous as when the liquid in the fermentor is thoroughly aerated, its apparent specific gravity drops. To maintain the proper flow ,of air through pipe 2| under such conditions, the volume of material passing through port 25 must be increased and this can easily be accomplished by enlargement of the diameter of the port as described above.

Mixing and agitating cones l3 and ii are secured to the shaft 3 by webs l4 and I6, respectively. Rotation of these cones in the liquid causes violent agitation by reason of the flow of liquid past the cones due to centrifugal action.

The foam breaker comprises cones 6 and I and disc 9, located above the normal liquid level in vessel I. Cone l is stationary and is supported by struts l1, I8. Cone 6 is secured to shaft 3 via web 8. A passage 3| is provided for flow of fluids between the cones. Beneath the cones a disc 9 is attached to shaft 3 through collar I 0. This disc is provided with an inner set of vanes In this inner set, vanes are turned up, while vanes II are turned down. The disc 9 is also provided with an outer set of vanes H, l2. In this set, vanes II are turned up and vanes 12 are turned down. Thus it is evident that the inner set of vanes is positioned in opposite relation to the outer set of vanes. The resu.t of this is that when the disc 9 is rotated counter clockwise, vanes 40 and 4| tend to force material up toward cone 6 while vanes H and I: tend to force material down toward the body of liquid in the vessel.

A convenient method of forming the vanes is by drilling holes 32, 33 in disc 9 then maki saw cuts along lines 34, 35, and 36. Flap 46 is then bent upwardly about 30 and flap 4| is bent downwardly about 30. madeinsimilar fashion.

The other vanes are In operatiomshaft 3 is rotated counterclockwise whereby the interior set of vanes 49, ll tend to force material upwardly while exterior vanes II, I I! tend to force material downwardly. Foam rising from the reaction mixture contacts the inner series of vanes 40, 4| whereby'the foam is thrown upwardly through the passage between adjacent vanes onto the inner surface of cone 6. The rotation of cone 6 forces material down again onto disc 9 beyond the inner series of vanes. Contact with the rapidly spinning disc forces material toward the walls of the vessel.

Some of the material is thrown downward by the outer series of vanes II, II. The flow of liquid and-gases produced by rotation of disc 9 causes a downdraft about the inner circumference of the'vessel whereby foam is pushed down at this point. Thus the rising body of foam has a dome-like structure and it appears ,that

v 4 the foam actually contacts the disc 9 only toward the center and in the vicinity of the interior set has been observed that cone 1 is not essential, al-' though it may be necessary if I the volume of foam suddenly increases and rises through cone 6. In such case, the foam will be directed back to the outer surface of cone 6 by disc .I.

The fermentor of this invention may be provided with conveniences to aid in control of the reaction. For instance, it is usually advisable to add a well for a thermometer, a well for an electrode to measure the pH of the reaction mixture and provide one or more sampling tubes. Such devices are easily mounted on lid 2 and pass through holes in cone I beyond the periphery of disc 9. A gas outlet is provided at 45. j

The apparatus of this invention can be u ed for growing all types of cultures under submerged conditions. For instance, it may be used for the production of yeasts such as baker's yeast, torula yeast, etc. It may be used for the production of antibiotics such as subtilin, penicillin, streptomycin, and other antibiotics produced by microorganisms. Further, the device may be used for the preparation of various chemical compounds such as citric acid, gluconic acid, acetic acid, and other compounds produced by micro-biosis. In all such cases the particular micro-organism is grown on the usual media and the use of the device of this invention gives more rapid and economical production.

\ Having described our invention, we claim:

1. A 'fermentor comprising a vessel, means for introducing a gas into the body ofliquid therein, comprising means in said vessel mounted for rotation about a vertical axis, said means providing an axial chamber, and providing lateral passageways communicating with said chamber, upwardly and outwardly extending vanes mounted for rotation with said passageways and mount ed adjacent said passageways, said axial chamber having a lower inlet communicating through a passageway with the body of liquid,

' a conduit communicating at one end with a source its lower end, the bore being the axial chamber,

the lateral passageways being tubes attached to, rotating with, and communicating with the bored end, the outer ends of the tubes'curving reare wardly, that is, opposite the direction of rotation, the outer portions of the vanes also curving rearwardly, whereby gas is drawn into the fermentor through the gas conduit, and means to adjust the distance between the said other end o! the gas conduit and the. lower inlet or the axial chamber.

HARRY HUMFELD. ERNST AESCHLIMANN. JOHN R. HOFFMAN.

REFERENCES CITED Number 6 UNITED STATES PATENTS Name Date Miller May 29, 1931 Mason June 23, 1931 Guest July 26, 1932 Bradford May 2, 1933 Jantzen et a1 July 24, 1934 Scholler June 8, 1937 Edwards June 4, 1946 Gates Aug. 6, 1946 

1. A FERMENTOR COMPRISING A VESSEL, MEANS FOR INTRODUCING A GAS INTO THE BODY OF LIQUID THEREIN, COMPRISING MEANS IN SAID VESSEL MOUNTED FOR ROTATION ABOUT A VERTICAL AXIS, SAID MEANS PROVIDING AN AXIAL CHAMBER, AND PROVIDING LATERAL PASSAGEWAYS COMMUNICATING WITH SAID CHAMBER, UPWARDLY AND OUTWARDLY EXTENDING VANES MOUNTED FOR ROTATION WITH SAID PASSAGEWAYS AND MOUNTED ADJACENT SAID PASSAGEWAYS, SAID AXIAL CHAMBER HAVING A LOWER INLET COMMUNICATING THROUGH A PASSAGEWAY WITH THE BODY OF LIQUID, A CONDUIT COMMUNICATING AT ONE END WITH A SOURCE OF THE GAS AND AT THE OTHER END WITH SAID LOWER INLET. 